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Biomedical subjects

T Fischer

Publications and source records attributed to T Fischer.

At least 73 records · Page 4Linked to original sources
PubMed2001

Modelling constant potential amperometry for investigations of dopaminergic neurotransmission kinetics in vivo.

Constant potential amperometry (CPA) was used for in vivo recording of extracellular dopamine (DA) after electrical stimulation of the medial forebrain bundle (MFB) (4 pulses, 2 mA, 20 or 100 Hz) in the striatum of the rat brain. CPA signals were analysed in the absence and presence of the DA uptake inhibitor nomifensine with the help of a mathematical model which considered both the influence of DA diffusion after its stimulated release and the Michaelis-Menten kinetics of cellular DA uptake from the extracellular space. We found an excellent conformity of experimentally obtained CPA signals and calculated curves. Mathematical analysis revealed that CPA signals were strongly influenced by DA diffusion. The kinetic parameters calculated from CPA signals in this study were in agreement with experimental determinations of Vmax and Km of extracellular DA uptake in other studies and reflect the particular pharmacological properties of nomifensine. CPA is a useful and efficient method for in vivo estimation of individual changes of DA kinetic parameters by pharmacological treatment.

Animals↗
PubMed2001

Application of different surface plasmon resonance biosensor chips to monitor the interaction of the CaM-binding site of nitric oxide synthase I and calmodulin.

Surface plasmon resonance biosensors depend on modified gold surfaces to allow immobilization of proteins or peptides for interaction analysis. We investigated sensor chip surfaces that differ in the geometry of the immobilization matrix: two contain a three-dimensional coupling matrix and two have a surface with immobilization sites on a two-dimensional plane. Properties of sensor chips were compared by studying the interaction of calmodulin with a peptide representing the calmodulin-binding site of nitric oxide synthase I. Apparent K(D) values were determined by three different procedures in order to apply tests for self-consistency. At low surface densities (5-8 fmol/mm(2)) on three of the four tested surfaces, estimated K(D) values were within one order of magnitude and similar to the value found in solution (K(D) = 1-3 nM). When immobilization densities were increased by one to two orders of magnitude, apparent association rate constants were less distorted on a flat carboxymethylated surface than on dextran-coated sensor chips.

Amino Acid Sequence↗
PubMed2001

Diagnosis of Heerfordt's syndrome by state-of-the-art ultrasound in combination with parotid biopsy: a case report.

The parotid gland is rarely affected by sarcoidosis (6% of all cases). If there is initial parotitis, and other major symptoms include fever, uveitis, or facial paralysis, the condition is referred to as Heerfordt's syndrome. The case presented here describes the diagnostic work-up and differentiation of swelling of the parotid gland by employing state-of-the-art ultrasound techniques in a 33-year-old patient with Heerfordt's syndrome. Color-coded duplex ultrasound demonstrated hypervascularization. Tissue harmonic and photopic imaging ultrasound additionally depicted hypoechoic, septated structural lesions of the glandular parenchyma with an optimized contrast. Since such structural changes are not a specific sonographic criterion for sarcoidosis, ultrasound-guided biopsy was performed for further clarification of the etiology of parotitis and for excluding lymphoma. In conclusion, state-of-the-art ultrasound with the option of obtaining a biopsy at low risk is a useful procedure for diagnosing unclear pathology of the parotid gland with rapid histological confirmation.

Adult↗
PubMed2001

Capillary leak syndrome in children who undergo cardiopulmonary bypass: clinical outcome in comparison with complement activation and C1 inhibitor.

OBJECTIVES: Capillary leak syndrome (CLS) is associated with significantly increased morbidity and occurs after cardiopulmonary bypass in children with congenital heart disease. We investigated the early clinical parameters that predict the development of CLS and examined the relationship between the presence of CLS and complement and contact activation and C1 esterase inhibitor (C1-INH) during and after bypass. DESIGN: In this prospective study we took serial serological measurements of the complement and contact system and C1-INH in a cohort of 27 infants before, during, and up to 96 h after open-heart surgery. RESULTS: Complement and contact activation and a decrease in C1-INH were measured in all infants during and after CPB. Ten infants developed CLS postoperatively. Younger age and longer bypass time were strongly correlated to the development of CLS. No relationship was found between the degree of hypothermia, weight, gender, or cross-clamp time. C1-INH concentration and activity were lower peri- and postoperatively in the CLS group. Infants with CLS had a more pronounced postoperative increase in the C5a and C3a levels, higher postoperative level of factor XIIa, and lower prekallikrein activity than those without CLS. CONCLUSION: Contact and complement activation occurs during cardiopulmonary bypass and contributes to CLS more frequently in infants of a younger age and with a prolonged bypass time. This activation and decrease in C1-INH was strongly expressed in the CLS group, and therefore early substitution of C1-INH may prevent CLS after open-heart surgery in high-risk infants.

Capillary Leak Syndrome↗
PubMed2001

The true value of the TRUE Test for allergic contact dermatitis.

The development of the thin layer rapid use epicutaneous (TRUE) Test is a history of cooperation between scientists from academia and industry covering several disciplines: medicine, pharmaceutical chemistry, pharmacology, and statistics. The TRUE Test is today a patch test system with documented stability and allergen content. Allergens are incorporated in a dried-in-gel vehicle, which is coated onto a polyester backing to form a patch. Applied to the skin, the allergens are released when the gel becomes moisturized by transepidermal water. This may seem to be a simple technique, but its development required laborious research and solutions to stability and dosage problems. The test has been clinically standardized with serial dilution tests on sensitized patients and validated in comparative multicenter tests. The test is a significant step towards higher reliability of patch testing. Fifteen years of experience and critical investigations are discussed in this article, as are possible improvements such as expansion of the test with new allergens.

Dermatitis, Allergic Contact↗
PubMed2001

HELLP syndrome in the 18th week of gestation in association with elevated angiotensin AT(1)-receptor autoantibodies.

We present a 24-year-old woman with a twin pregnancy who was with a typical HELLP syndrome at the 18th week of pregnancy. One fetus was dead, while the other was severely growth retarded. Our patient had agonistic autoantibodies directed at the angiotensin AT(1)-receptor. Termination of the pregnancy proved necessary. This report is the first to our knowledge associating HELLP syndrome with angiotensin AT(1)-receptor antibodies. Since the antibodies may have a pathogenic significance, their removal could permit the prolongation of pregnancy in preeclamptic and HELLP syndrome patients.

Adult↗
PubMed2001

Dual diagnosis and successful participation of adolescents in substance abuse treatment.

A retrospective record review of one year of admissions to a residential adolescent substance abuse treatment program (N = 91) examined the prevalence of comorbid psychiatric disorders and factors associated with successful treatment participation. Psychiatric and substance use disorders (SUD) were diagnosed by DSM-IV criteria. Successful participation was based on multiple factors assessed by the treatment team. Consistent with prior studies, there was considerable comorbidity (63.7%) with both disruptive (Attention Deficit Hyperactivity Disorder [ADHD], 11%; Conduct Disorder [CD], 24%) and other disorders (depression, 24%; adjustment disorder, 7.7%; bipolar disorder, 3.3%). Male gender was negatively associated (OR = 0.23, P = 0.019) with successful participation in univariate analyses, as was ADHD (OR = 0.18, P = 0.007). CD (OR = 0.37, P = 0.053) approached significance. Multivariate analysis reveals ADHD was significant while having CD and being male approached significance. Psychotropic medication use and other diagnoses were not associated with successful participation. It is concluded that further research on the relationship between ADHD, CD, and substance abuse treatment is needed.

Adolescent↗
PubMed2001

Hemorheology and renal function during cardiopulmonary bypass in infants.

BACKGROUND: Acute renal failure is an occasional complication after cardiopulmonary bypass in infants. Whereas it is well known that postoperative hemodynamics inflict acute renal failure, the influence of extracorporeal circulation on the kidney is less clear. Moreover, changes in blood viscosity occur during and after surgery, which may influence renal dysfunction. For this reason, we investigated the impact of blood viscosity on renal function during cardiopulmonary bypass. METHODS: In 34 patients weighting less than 10 kg, we performed repeated analysis of urine, blood, and plasma viscosity. RESULTS: Polyuria and proteinuria that appeared during cardiopulmonary bypass indicated an elevated transglomerular filtration gradient, which recovered within 24 hours. The appearance of N-acetyl-beta-D-glucosaminidase in the urine, and elevated excretion of sodium, were additionally indicative of mild tubular damage. Elevation of blood viscosity during hypothermic perfusion showed a statistical correlation with proteinuria and N-acetyl-beta-D-glucosaminidaseuria. With hypothermia, the relation of blood viscosity to plasma viscosity became stronger, while the relation to the hematocrit decreased compared to normothermia. CONCLUSIONS: During cardiopulmonary bypass perfusion, the kidney can be stressed by proteinuria and mild tubular damage. Our data provide evidence that the kidneys can be protected by improved blood viscosity during cardioplegia, but this needs confirmation in a prospective interventional study.

Acetylglucosaminidase↗
PubMed2001

Fragrance contact dermatitis: a worldwide multicenter investigation (Part II).

The purpose of this study was to determine the frequency of responses to selected fragrance materials in patients who were fragrance sensitive. 178 patients were evaluated in 8 centers worldwide with a fragrance mix (FM) and 20 other fragrance materials. Reaction to the fragrance mixture (FM) occurred in 78.7% of the subjects. Substances reacting at a rate of 2% or higher included jasmine absolute, geranium oil bourbon, l-citronellol, spearmint oil, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-benzopyran, omega-6-hexadecenlactone, dimethyltetrahydrobenzaldehyde (isomer mixture), and alpha-amylcinnamaldehyde. These chemicals should be furthur evaluated to corroborate their allergenicity. We are constantly looking for new fragrance allergens to extend the diagnostic capability of the fragrance mix (FM).

Allergens↗
PubMed2001

Fatal sepsis due to mycobacterium tuberculosis after allogeneic bone marrow transplantation.

Mycobacterium tuberculosis is a serious, but rare infectious complication after allogeneic bone marrow transplantation. We describe a case of fatal sepsis due to Mycobacterium tuberculosis after allogeneic bone marrow transplantation for Philadelphia chromosome-positive ALL. The diagnosis was made after BAL. Although broad-spectrum antituberculous therapy was started immediately after diagnosis, blood cultures became positive for Mycobacterium tuberculosis. The patient developed severe pyrexias and finally died of multi-organ failure. Rapid progression of mycobacterial infection should be considered in patients post BMT with unexplained fever, particularly in patients from endemic areas.

Adult↗
PubMed2001

Failure of sustained engraftment after non-myeloablative conditioning with low-dose TBI and T cell-reduced allogeneic peripheral stem cell transplantation.

We investigated whether a T cell-reduced allogeneic stem cell transplant (SCT) with minimal conditioning and subsequent donor lymphocyte infusions (DLI) could reduce the incidence and severity of GVHD while retaining stable engraftment. Five patients with hematological malignancies (three MM, one CLL, one Chediak-Higashi syndrome) were conditioned with TBI (200 cGy). One patient additionally received fludarabine (120 mg/m(2)). CsA and mofetyl-mycophenolate (MMF) were administered to prevent GVHD. All patients were grafted with >3 x 10(6)/kg highly purified CD34(+) cells together with 2 x 10(6)/kg CD3(+) cells (three patients) or 1 x 10(5)/kg CD3(+) cells (two patients). Quick hematopoietic recovery and initial mixed donor chimerism was observed. Treatment-related toxicity was minimal in all but one patient who died of treatment-refractory GVHD on day 112. The four other patients only achieved partial donor T cell chimerism. BM and PBMC donor chimerism was lost between day 40 and 209 despite DLI. Three patients are alive with disease and one is in CR. We conclude that T cell-reduced SCT using 200 cGy as the conditioning regimen does not result in stable hematopoietic engraftment. Predominant donor T cell chimerism is not a prerequisite for initial allogeneic hematopoietic proliferation. However for sustained long-term engraftment it is of major importance.

Adult↗
PubMed2001

[Distal pedicled sural island flap-plasty for defect coverage of the distal lower extremity].

Soft tissue defects on the distal lower extremity often need extended reconstructive procedures, especially if tendinous, articular, or bony structures are exposed. The use of local flaps in the perimalleolar, pretibial and calcaneal area is limited, often free tissue transfer is required. The distally based sural island flap is a pedicled soft-tissue flap on the vascular axis of the sural nerve. It can be raised as a fasciocutaneous or a lipofascial flap. We report our experience of 16 cases, nine of these cases in the lipofascial technique. The aim of soft tissue coverage was reached in 15 cases. In one patient a partial necrosis of the flap occurred requiring a reoperation with free flap coverage. The main advantages of the technique are the extended arc of rotation in the problematic area of the ankle and the lower extremity, the easy and fast preparation and the stable flap perfusion. The lipofascial as well as the fasciocutaneous flap have some risk of loss or donor-site morbidity that can be avoided by adhering strictly to certain operative principles.

Adolescent↗
PubMed2001

[Contribution of MRI in diagnosis of urinary stress incontinence without concomitant urogenital prolapse].

PURPOSE: To detect pathomorphological changes of the pelvic floor, the vagina, and the urethra by MR imaging in patients with stress urinary incontinence in the absence of organ descent compared with findings in 10 healthy controls. MATERIALS AND METHODS: The study included 10 healthy controls and 38 patients with stage II urinary incontinence showing no urge symptoms but a pathological stress profile on urodynamic testing. The subjects underwent MR imaging with a phased-array coil at 1.5 T in addition to urodynamic testing and gynecological examination. The following sequences were used: axial and coronal PD-weighted TSE sequences with a FOV of 20 cm and a section thickness of 4 mm; axial STIR sequence. Sagittal T2-weighted HASTE sequences were acquired during pelvic floor contraction, relaxation, and straining maneuvers. RESULTS: In 22/38 cases pathomorphological changes were found by MR imaging. The pathomorphological changes were classified as lateral defects (n = 14) if the musculofascial connection between the levator muscle and the lateral vaginal wall or the butterfly shape of the vagina was absent and as central (n = 16) if changes were detected in the urethral wall. Defects of the pelvic floor muscles were detected in 8 cases. No underlying changes were identified in 16/38 cases. CONCLUSION: In cases of female urinary incontinence, MR imaging of the pelvic floor can detect pathomorphological changes, which are difficult to identify by clinical examination. MR imaging currently does not allow the detection of morphological changes in all forms of female urinary stress incontinence.

Adult↗
PubMed2001

Surface contamination to UV-curable acrylates in the furniture and parquet industry.

Surface contamination to ultraviolet radiation curable coatings (UV coatings), used increasingly in the parquet and furniture industry, is a matter of concern as a source for skin contamination. UV coatings contain chemically and biologically reactive acrylates, well known as skin contact irritants and sensitizers. Surface contamination may spread secondarily to equipment and other unexpected areas even outside the workplace. Yet, studies concerning this type of contamination are lacking due to lack of suitable sampling methods. Surface contamination of the work environment with risk for skin exposure to UV coating was measured employing a quantitative adhesive tape sampling method developed for this purpose. A pilot study was first performed at three workplaces to evaluate the contamination. In the main study, we wanted to locate and identify in detail the surface contamination of areas where problems exist, and to determine the extent of the problem. Measurements were performed at seven workplaces on two separate workdays (round 1 and 2) within a six-month period. Samples were collected from the workplaces based on the video monitoring of skin contact frequency with the surfaces and categorized into three groups to analyze risk. The pilot study indicated that surface contamination to TPGDA containing UV coatings was common, found in 76 percent of the surfaces, and varied with a maximum of 909 microg TPGDA 10 cm(-2) sampling area. In the main study TPGDA was found in 153 out of 196 collected samples (78.1%); for round one 78.1 percent (82 out of 105 samples) and for round two 78.0 percent (71 out of 91 samples). The average TPGDA mass on positive surface samples was on the first round 2,247 +/- 7,462 microg, and on the second round 2,960 +/- 4,590 microg. We conclude that surface contamination to uncured UV coatings at UV-curing lines is common and this involves a risk for harmful, unintentional skin exposure to acrylates.

Acrylates↗
PubMed2001

Anticoagulation during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II and renal impairment using heparin and the platelet glycoprotein IIb-IIIa antagonist tirofiban.

BACKGROUND: Patients with heparin-induced thrombocytopenia type II require an alternative to standard heparin anticoagulation. However, in patients with renal impairment, anticoagulation during cardiopulmonary bypass with agents such as danaparoid sodium or r-hirudin are associated with hemorrhage. Anticoagulation with unfractionated heparins combined with prostacyclin, a potent platelet aggregation inhibitor, is associated with severe hypotension. The authors investigated a new concept using unfractionated heparins after platelet inhibition with the short-acting platelet glycoprotein IIb-IIIa antagonist tirofiban. METHODS: Ten patients with heparin-induced thrombocytopenia type II and renal impairment were enrolled in the investigation. All had heparin-induced thrombocytopenia type II antibodies present as proved by the heparin-induced platelet aggregation assay, the heparin-platelet factor 4 enzyme-linked immunosorbent assay, or both. In all patients, preoperative anticoagulation to an activated partial thromboplastin time of 40-60 s was performed with r-hirudin. Anticoagulation during cardiopulmonary bypass was achieved with a bolus of 400 IU/kg unfractionated heparins after a bolus of tirofiban 10 microg/kg followed by an infusion of tirofiban at a rate of 0.15 microg x kg(-1) x min(-1) until 1 h before conclusion of cardiopulmonary bypass. Additional unfractionated heparins were only administered if activated clotting time decreased below 480 s. Coagulation was monitored by a abciximab-modified TEG and the adenosine diphosphate-stimulated (20 microm) platelet aggregometry. D-dimer concentrations, as a marker of venous thromboembolism, were measured before and 12, 24, and 48 h after surgery. Postoperative antithrombotic therapy was started immediately with r-hirudin to anticoagulation to an activated partial thromboplastin time of 40-60 s. RESULTS: The postoperative blood loss ranged from 110 to 520 ml. No patient needed reexploration. In no patient was there clinical evidence of thrombosis or embolism in the postoperative period or of a critical increase of the D-dimer concentrations, suggesting venous thromboembolism. Transfusion of platelets was necessary in only two patients. CONCLUSIONS: The protocol is easy to perform and no increased postoperative bleeding and no thromboembolic complications occurred. The combination of unfractionated heparins and tirofiban may be an alternative to other anticoagulation strategies in patients with heparin-induced thrombocytopenia.

Adult↗
PubMed2001

Experience in upper eyelid reconstruction with the Cutler-Beard technique.

Reconstruction of full-thickness upper eyelid defects has to supply a movable lid with perfect corneal protection, good aesthetic quality, and acceptable sequelae at the donor site. The Cutler-Beard procedure, a full-thickness cutaneoconjunctival inferior eyelid advancement flap, is a reliable method for reconstruction of total or partial upper eyelid defects. Especially in older individuals, the skin of the donor site is loose and provides sufficient tissue to stretch. Color and texture of the donor matches the recipient site perfectly. Destabilization or ectropion of the donor site, the lower lid, and retraction or entropion of the recipient site, the upper lid, are the main complications. Therefore, a modification of the classic technique should be considered by implantation of an enforcing inlay in the reconstructed lid (eye bank sclera, fascia lata, ear cartilage), especially in reconstruction of extended defects of the upper lid.

Aged↗